Ducted air power plant

ABSTRACT

A ducted air power plant, comprising a motor driven fan ( 7 ) situated in a duct ( 4 ), the fan ( 7 ) having an air intake side and in operation providing a high pressure air stream in the duct, and the fan being located adjacent air splitter mechanism ( 18 ), the air splitter mechanism ( 18 ) being arranged to divert the air stream into two or more subsidiary streams for delivery to respective jet nozzles ( 9 ) of the plant. The plant may be used in a vehicle such as an aircraft in order to provide a vertical take-off and hover capability as well a level flight power source.

This application is a national stage completion of PCT/GB2003/002770filed Jun. 27, 2003 which claims priority from British ApplicationSerial Nos. 0214961.5 and 0301177.2 filed Jun. 28, 2002 and Jan. 20,2003, respectively.

FIELD OF THE INVENTION

This invention relates to a ducted air power plant. It relatesparticularly to a power plant for an aircraft or airship which makes useof movable jet nozzles with variable thrust for controlling the craft'sposition and attitude. Alternative uses for the power plant include aplatform having hovering facilities suitable for carrying equipment suchas a camera or fire extinguishing chemicals. An additional possibilityis the provision of a freely movable platform for providing aerialobservation information.

The principle of using movable jet nozzles in an aircraft to provideinitially lift-off and then forward acceleration was disclosed in patentspecifications GB861480, GB3899862 and GB905651 (Hawker). Thesespecifications describe an arrangement of vectoring nozzles whichdeflect the engine's thrust so that they will be turned partiallydownward to provide lift-off. After this stage, the nozzles are rotatedto provide forward acceleration and at a sufficiently high speed thenecessary lift is obtained entirely from the aircraft wings. The nozzleswill then be brought into a fully aft position so that they will bedevoted solely to producing the forward movement.

The transition between the nozzles being directed for vertical thrustand then rearward thrust needs to be effected with great care so thatthe aircraft will be maintained in a generally horizontal attitudethroughout. At speeds lower than the wing borne air speed, the aircraftattitude is sometimes capable of being adjusted by secondary nozzleslocated at the wingtips, nose and tail which are under the control of apilot. If side winds are present at take-off, the aircraft attitude willneed to be supervised particularly carefully. In the full size aircraft,this is the mechanism that is used to maintain stability through thesetransitions. However, if the aircraft is represented in a model aircraftversion, this mechanism is not available and all the control adjustmentshave to be executed by adjusting the thrust exiting from each nozzle.

The nozzle arrangement disclosed in the aforementioned specifications isthe provision of four nozzles, two of which are located in front of theaircraft centre of gravity and two are located behind this point. Thenozzles are positioned on the port and starboard sides of the aircraftso that a relatively stable platform will be formed.

According to the invention, there is provided a ducted air power plant,the power plant comprising a motor driven fan situated in a duct, thefan having an air intake side and in operation providing a high pressureair stream in the duct, and the fan being located adjacent air splittermeans, the air splitter means being arranged to divert the airstreaminto two or more subsidiary streams for delivery to respective jetnozzles of the plant. Preferably, the air splitter means is an airsplitter plate arranged to provide four subsidiary air streams.

The delivery of the subsidiary streams from the air splitter plate tothe jet nozzles may be effected through respective air delivery tubeshaving a circular, elliptical or other cross-section.

The fan rotor may be located adjacent a fan stator blade unit arrangedto reduce the degree of rotation (or swirl) present in the air streamleaving the fan. The air splitter plate may be located with one or moreair control blades which may be moved to enable the individual flow ofair to each jet nozzle to be adjusted.

Preferably, the air control blades are positioned immediately in frontof the air splitter plate. Each blade may be balanced for rotation aboutan axis which is in line with a diagonal of the air splitter plate, suchdiagonal being located where it will offer minimum obstruction to theair flow through an air flow opening of the plate.

The invention also comprises a mobile platform vehicle mounted with thepower plant. It further comprises an aircraft including the power plant.

BRIEF DESCRIPTION OF THE DRAWINGS

By way of example, a particular embodiment of the invention will now bedescribed with reference to the accompanying drawings, in which:

FIG. 1 is an end perspective view of the ducted air power plant,

FIG. 2 is a similar view taken from the opposite side of the plant andpartly cut away,

FIG. 3 shows the power plant engine with front engine casing piecesremoved,

FIG. 4 depicts an air splitter plate with the ducted fan stator blades,

FIG. 5 shows the air splitter plate with air control blades,

FIG. 6 shows the air splitter plate,

FIG. 7 shows four views of a different embodiment of air splitter plate,

FIG. 8 is a perspective view from one end of the air splitter plateshowing the air control blades in place,

FIG. 9 is a view of the plate from the opposite end showing the aircontrol blades,

FIG. 10 is a partial cross-sectional view showing how tilting of an aircontrol blade can divert an air stream from one passage to another ofthe air splitter plate,

FIG. 11 shows the air control blade and servo motor combination in fourviews taken from different sides,

FIG. 12 shows one aircraft construction using the ducted air power plantof the invention, and,

FIG. 13 is a plan view of the power plant with the nozzles directed toproduce a yaw motion of the unit.

DETAILED DESCRIPTION OF THE INVENTION

The construction of the ducted air power plant of the invention beginswith making a choice of the engine to be used. In the present example,this was a two-stroke water-cooled internal combustion engine havingglow plug ignition and a rotational speed of up to 28,000 RPM. The FIGS.1 and 2 views show the engine mounted with an axial flow fan rotorcarried directly on the output shaft of the engine. In the figures, theengine has a working cylinder 1 and aligned at right angles to this theoutput shaft 2 is located. The engine is also provided with an exhaustsilencer 3 and the usual working components including a fuel tank withcarburettor. The FIG. 1 view shows the fan rotor being surrounded by acasing 4 which serves to confine the pressurised air flow produced bythe fan. In the FIG. 2 view, the casing 4 is shown with a minormodification which provides a bell-shaped opening 6 at the air entryend.

Mounted at the end of the engine output shaft 2 is the fan rotor 7 theblades of which are aligned to drive air in the direction of thecylinder 1. The incoming air stream is divided into four streams by anair splitter plate 8 and these streams are delivered to adjustable jetnozzles, two of which nozzles 9 can be seen at the left hand side of theFIG. 1 view.

The nozzles 9 are located at the ends of air delivery tubes 11 whichconvey the four air streams from the air splitter plate 8 to the fournozzles 9. The adjustment of the nozzles is effected by rotating eachnozzle 9 about the end of its delivery tube 11 so that the nozzle may beturned in order to deflect its respective air stream forwards, downwardsor rearwards. The rotation of each nozzle is done by operation of afirst servo motor 12 alongside the nozzle. There are four of the firstservo motors 12, one being provided for each of the nozzles 9. Air guidevanes may or may not be incorporated in the ducts and/or nozzles toimprove the airflow efficiency and reduce the airflow losses.

FIG. 3 shows further details of the construction where the front casing4 pieces have been removed and the nozzles at the left hand side of theengine have been omitted. Just downstream of the fan rotor 7, a fixedblade air straightener comprising fan stator blades 13 is positioned toreduce the amount of rotation (or swirl) which is present in the airstream leaving the fan. The air splitter plate 8 is mounted across theair stream with four passages arranged such that the stream will bedivided into the four separate streams for delivery to the nozzles 9(FIG. 1). The shaping of the air splitter plate is such that theincoming air streams will be divided substantially equally into the foursmaller streams in a fairly smooth and streamlined manner. This iseffected partly by a funnel-like entry opening 14 being provided at theupstream side of each air splitter passage.

FIG. 4 shows the air splitter plate 8 with the ducted fan stator blades13 mounted on a boss at the front end of the plate 8. Also at the frontend of each air splitter passage, the air splitter plate supports an aircontrol blade 16 which is mounted on a surface in front of the passages.There are four air control blades and these are positioned between eachpair of passages through which the smaller air streams pass. Therefore,if an air control blade should be positioned in line with the air flowthrough its pair of passages then there will be an equal flow of airthrough the two passages. However, if an air control blade should bealigned at a small angle to the direction of air flow, then the air flowthrough one of the passages will be reduced whilst the flow through theother passage will be increased. There are four air splitter passageswith an air control blade located between each pair of passages so thisconstruction allows a wide degree of adjustment to be made to the volumeof air passing through the individual passages.

FIG. 5 shows the air splitter plate 8 supporting the four air controlblades 16. Each air control blade is in contact at its inner end withits surface 17 and the outer end of each blade is movable about an axisradial to the engine output shaft by a second servo motor 18 (FIG. 1).The second servo motors 18 are thus supported on the casing 4 pieceswhich in operation surround the fan assembly.

The air splitter plate 8 also carries the cylindrical boss 19 which isprovided with splines so that the fan stator blades 13 will be able tobe supported in a rigid manner. The engine output shaft 2 (FIG. 2), ofcourse, passes through the air splitter plate 8 so that the fan rotor 7will be able to be secured to the end of the shaft.

The downstream side of the air splitter plate 8 carries fixing means 21(FIG. 3) by which the air delivery tubes guiding the four air streamsare attached to the plate. As depicted in FIG. 1, there are two airdelivery tubes 11 located on the left hand side of the engine and twofurther tubes (not visible in the FIG. 1 view) on the right hand side.Each of the air delivery tubes terminates in its own nozzle 9 and thetwo nozzles visible in the FIG. 1 view are shown directed downwards sothat they will produce a jet thrust reaction tending to raise the powerplant on that side. A similar effect will occur from the nozzles on theopposite side of the power plant. However, each of the nozzles isrotatable about the end of the air delivery tube which supports thenozzle. The positioning of each nozzle is adjusted by the provision ofthe respective first servo motor 12 for each nozzle. It will thus bepossible for all of the nozzles to generate upward thrust if this isrequired or possibly a combination of forward and upward thrust if thenozzles have been suitably positioned by their servo motors.

FIG. 6 shows the air splitter plate 8 after the air control blades 16have been removed from the surfaces 17.

FIG. 7 shows four views of a different embodiment of air splitter plate8. It will be seen that the two air passages on the upper portion of theplate are spaced apart from one another by a particular distance, whilstthe two passages in the lower portion of the plate are spaced closelytogether. This arrangement allows the relevant air delivery tubes to bepassed round the mass of the engine.

FIG. 8 is a perspective view from one end of the air splitter plateshowing the air control blades in place.

FIG. 9 is a view from the opposite end of the air splitter plate withthe air control blades in place. It will be noticed that the two sets ofair control blades 16 whose tilting axis 20 is located on a horizontalline are spaced closer to the upper two air passages than they arespaced to the lower two passages. This, similarly, allows the airdelivery tubes to pass round the mass of the engine.

FIG. 10 is a partial cross-sectional view of the air control blade beinglocated between two passages in the air splitter plate 8. There are airpassages located at the left hand side and right hand side of theFigure. It is apparent that the tilting of the uppermost air controlblade 16 in an anticlockwise direction has caused part of the air streamthat would have flowed through the right hand passage to be divertedinto the left hand passage. When the air control blade is returned to aposition in line with the incoming air stream this will again permitequal volumes of air to pass through both passages.

FIG. 11 shows four views of an air control blade 16 with its own secondservo motor 18. The servo motor 18 has an output shaft which isconnected by a bevel gear drive to its air control blade 16 so thatactuation of the motor will cause the control blade to be rotatedthrough a small angle. Each air control blade 16 is seen to have abox-like construction with a rectangular sleeve and a central partition.Each air control blade 16 thus forms two parallel passages for airstreams and by rotating this box, the streams will be able to bedirected to either side about the axis of the rotating action.

FIG. 12 shows one aircraft construction in which the ducted air powerplant of the invention has been incorporated. In this instance, theaircraft is a Hawker aircraft as disclosed in one of the aforementionedpatent specifications. The aircraft is of a short take off and landingdesign and it is provided with a forward facing air intake 23, one ofthese being located on each side of the fuselage. The aircraft also hastwo forward jet nozzles 24 and the same number of rearward jet nozzles26. The nozzles are rotatable as already mentioned and, in thearrangement depicted in the Figure, the nozzles have been directedforward and partly downward to give reverse thrust for manoeuvring andbraking purposes.

A control system for the power plant was devised which could be mountedin a model aircraft and which was capable of being operated under radiocontrol by a standard commercially available radio transmitter. Theaircraft was provided with full operational functions for motor control,rudder, elevators, ailerons, flaps, pitch and roll hover controls. Theaircraft was thus able to hover and to make the transition from hover toforward flight and back again. A sensor based control system wasincorporated. The first and second servo motors 12, 18 were driven by acomputer controlled system so that the nozzles and the air controlblades would be adjustable independently of one another. In fact, theair control blades were arranged to be controlled in pairs so that oneset of air control blades will be moved simultaneously with thecorresponding set of blades on the opposite side of the engine shaft.

In the construction of the ducted air power plant, it was found possiblefor many of the components to be made either by a carbon-fibre compositeor a plastics injection moulding process in the interest of keepingweight to a minimum. The ducting, the air control blades, enginemountings, the nozzles, the rotor and stator fan units, and the airsplitter plate were made by one or other of these processes. The aircontrol blades 16 each comprise a hollow box-like construction of threeaerodynamically designed blades linked by top and bottom members.Preferably, the outer blades are splayed slightly outwards to improveaerodynamic efficiency of the blades during rotation.

In operation of the ducted air power plant, this has been found suitablefor incorporation in an aircraft fuselage similar to the Hawker aircraftdepicted in FIG. 12. With a suitable radio control unit mounted in theaircraft to control the operation of the engine, elevators, flaps andservo motors, this can enable a flying model to be taken throughrealistic maneouvres. These can include vertical take-off and landing,transition to forward flight, transition back to hover, landing andflight backwards.

A further useful movement in an aircraft of this type is the yaw motionwhich is an angular motion of the aircraft in a horizontal plane aboutthe normally vertical axis. In the Hawker aircraft, a couple to generatethe yawing moment is provided by directing a high velocity air streamthrough reaction control valves located in the nose and the rear boom ofthe aircraft fuselage. By contrast, in the aircraft of the presentinvention, the yaw moment is provided by turning the two left handfuselage side nozzles in one direction and the two hand nozzles in theopposite direction. The yaw moment is thus delivered through the use ofa counter rotated nozzle alignment.

FIG. 13 gives a plan view of the power plant with the two left sidenozzles 9 (on the upper part of the Figure) rotated in a forwarddirection and the two right side nozzles 9 (on the lower part of theFigure) rotated in a rearward direction. The thrust will thus bedirected to cause the aircraft to rotate in an anticlockwise directionabout the vertical axis.

Additionally, when in the hover attitude, as the aircraft moves awayfrom its centre point in either the pitch or roll planes, the nozzlesare able to be individually adjusted so that they are always positionedvertically downwards with regard to the ground surface. This provisioncan help to ensure that the maximum jet thrust is being deliveredvertically downwards in order to sustain a stable hover of the aircraft.

The foregoing description of an embodiment of the invention has beengiven by way of example only and a number of modifications may be madewithout departing from the scope of the invention as defined in theappended claims. For instance, instead of the power source being a twostroke internal combustion engine, the source may be a brushlesselectric motor with a motor controller and fuel cell or rechargeablebattery. A miniature gas turbine type of engine is a furtherpossibility. In addition, the air control blade component has beendescribed as being of a hollow box construction supporting threeaerodynamic air deflector blades. In a different embodiment, the aircontrol blade component could have more or less than this number of airdeflector members.

It is also possible to provide an alternative construction of powerplant where the air stream would be delivered down a central duct withmovable air control blades being located diagonally opposite one anotherin the duct. The air control blades would then act to divert part of thestream into one or both of a left or right hand side air delivery tube.This construction thus could be used on an aircraft having only threejet nozzles.

In order to significantly improve the operating performance of thetwo-stroke engine and allow an indefinitely sustainable hover flight, acooling system has been introduced for both the engine head and exhaustmanifold/tuned pipe. Water, ethylene glycol or similar coolant fluid iscirculated through these components by means of cooling ducts connectedto a pump, the pump being either driven directly from the engine driveshaft or remotely operated by an electric motor. The hot coolant is thenrecirculated around a heat exchanger formed by the ducted fan shroud andair delivery tubes which are fabricated from aluminium, carbon fibrecomposite or similar material, having good heat conduction properties.The effect of the high speed air being forced through the inner side ofthis duct provides cooling to extract the required quantity of heat fromthe coolant fluid. A further benefit of the heat exchanger is that inexpanding the air as a result of heat transfer as it travels through therear air delivery tubes, the thrust at a jet nozzle exit will beincreased to a small extent. During flight, the external skin of thisheat exchanger will be exposed to air being forced over it from airentering just behind the air intakes. This effect can further increasethe effectiveness of the available cooling.

1. A ducted air power plant comprising: a motor-driven fan for producinga high-pressure air stream; air splitter means for deriving a pluralityof subsidiary air streams from the high-pressure air stream; a pluralityof vectoring air-jet nozzles; and means for ducted delivery of thesubsidiary air streams to respective ones of the vectoring air-jetnozzles; the air splitter means comprises selectively-adjustablesplitter means for splitting the high-pressure air-stream proportionallybetween the subsidiary air streams, the selectively-adjustable splittermeans being selectively adjustable to vary the proportions with whichthe high-pressure air stream is split between the respective subsidiaryair streams; the selectively-adjustable splitter means comprises asplitter plate, the splitter plate defining first and second duct-entryopenings for receiving individual ones of the subsidiary air streams, acontrol-blade device mounted for angular displacement relative to thefirst and second duct-entry openings, and means for selectivelyadjusting the angular displacement of the control-blade device forvarying the proportions by which air of the high-pressure air-stream issplit between the first and second duct-entry openings; and thecontrol-blade device comprises means defining a plurality of parallelpassages for directing air of the high-pressure air stream into thefirst and second duct-entry openings in relative proportions dependenton the angular displacement of the control-blade device relative to thefirst and second duct-entry openings.
 2. A ducted air power plantcomprising: a motor-driven fan for producing a high-pressure air stream;air splitter means for deriving a plurality of subsidiary air streamsfrom the high-pressure air stream; a plurality of vectoring air-jetnozzles; and means for ducted delivery of the subsidiary air streams torespective ones of the vectoring air-jet nozzles; wherein the airsplitter means comprises selectively-adjustable splitter means forsplitting the high-pressure air-stream proportionally between thesubsidiary air streams, the selectively-adjustable splitter means beingselectively adjustable to vary the proportions with which thehigh-pressure air stream is split between the respective subsidiary airstreams, and wherein the selectively-adjustable splitter means comprisesa splitter plate, the splitter plate defining four duct-entry openingsfor individual ones of the subsidiary air streams, four control-bladedevices each associated with a respective pair of the four duct-entryopenings, each control-blade device being mounted for angulardisplacement relative to the two duct-entry openings of itsrespectively-associated pair of duct-entry openings to vary theproportions by which the high-pressure air-stream is split between thetwo duct-entry openings of the pair of duct-entry openings associatedwith that respective control-blade device, and means for selectivelyadjusting the angular displacement of each control-blade device forvarying the proportions by which the high-pressure air-stream is splitbetween the two duct-entry openings of the pair of duct-openingsassociated with that respective control-blade device.
 3. A ducted airpower plant comprising: a motor-driven fan for producing a high-pressureair stream; air splitter means for deriving a plurality of subsidiaryair streams from the high-pressure air stream; a plurality of vectoringair-jet nozzles; and means for ducted delivery of the subsidiary airstreams to respective ones of the vectoring air-jet nozzles; wherein theair splitter means comprises selectively-adjustable splitter means forsplitting the high-pressure air-stream proportionally between thesubsidiary air streams, the selectively-adjustable splitter means beingselectively adjustable to vary the proportions with which thehigh-pressure air stream is split between the respective subsidiary airstreams; wherein the selectively-adjustable splitter means comprises asplitter plate, the splitter plate defining four duct-entry openings forindividual ones of the subsidiary air streams, four control-bladedevices each associated with a respective pair of the four duct-entryopenings, each control-blade device being mounted for angulardisplacement relative to the two duct-entry openings of itsrespectively-associated pair of duct-entry openings, and means forselectively adjusting the angular displacement of each control-bladedevice for varying the proportions by which the high-pressure air-streamis split between the two duct-entry openings of the pair ofduct-openings associated with that respective control-blade; and whereineach control-blade device comprises means defining a plurality ofparallel passages for directing air of the high-pressure air stream intothe two duct-entry openings of its associated pair of duct-entryopenings.
 4. The ducted air power plant according to claim 2, includingfour servo motors for controlling the angular displacements respectivelyof the four control-blade devices.
 5. The ducted air power plantaccording to claim 2, including straightening blades for straighteningflow of high-pressure air from the motor-driven fan.
 6. A craft having aVTOL capability, the craft incorporating a ducted air power plant, andthe ducted air power plant comprising: two pairs of vectoring air-jetnozzles, the two nozzles of each pair being spaced apart laterally onopposite sides of the craft and the two pairs of nozzles being spacedapart forward and rearward of the craft; a motor-driven fan forproducing a high-pressure air stream; air splitter means for splittingthe high-pressure air stream into four subsidiary air streams; and meansfor ducted delivery of the four subsidiary air streams to the fourvectoring air-jet nozzles respectively; wherein the air splitter meanscomprises selectively-adjustable splitter means for splitting thehigh-pressure air-stream proportionally between the four subsidiary airstreams, the selectively-adjustable splitter means being selectivelyadjustable to vary the proportions with which the high-pressure airstream is split between the four subsidiary air streams; and wherein thenozzles of the four vectoring air-jet nozzles are vectored by respectiveservo-motor controls, and wherein the selectively-adjustable splittermeans comprises a splitter plate, the splitter plate defining fourduct-entry openings for individual ones of the subsidiary air streams,four control-blade devices each associated with a respective pair of thefour duct-entry openings, each control-blade device being mounted forangular displacement relative to the two duct-entry openings of itsrespectively-associated pair of duct-entry openings to vary theproportions by which the high-pressure air-stream is split between thetwo duct-entry openings of the pair of duct-entry openings associatedwith that respective control-blade device, and means for selectivelyadjusting the angular displacement of each control-blade device forvarying the proportions by which the high-pressure air-stream is splitbetween the two duct-entry openings of the pair of duct-openingsassociated with that respective control-blade.
 7. A craft having a VTOLcapability, the craft incorporating a ducted air power plant, and theducted air power plant comprising: two pairs of vectoring air-jetnozzles, the two nozzles of each pair being spaced apart laterally onopposite sides of the craft and the two pairs of nozzles being spacedapart forward and rearward of the craft; a motor-driven fan forproducing a high-pressure air stream; air splitter means for splittingthe high-pressure air stream into four subsidiary air streams; and meansfor ducted delivery of the four subsidiary air streams to the fourvectoring air-jet nozzles respectively; wherein the air splitter meanscomprises selectively-adjustable splitter means for splitting thehigh-pressure air-stream proportionally between the four subsidiary airstreams, the selectively-adjustable splitter means being selectivelyadjustable to vary the proportions with which the high-pressure airstream is split between the four subsidiary air streams; and wherein thenozzles of the four vectoring air-jet nozzles are vectored by respectiveservo-motor controls; wherein the selectively-adjustable splitter meanscomprises a splitter plate, the splitter plate defining four duct-entryopenings for individual ones of the subsidiary airstreams, fourcontrol-blade devices each associated with a respective pair of the fourduct-entry openings, each control-blade device being mounted for angulardisplacement relative to the two duct-entry openings of itsrespectively-associated pair of duct-entry openings, and means forselectively adjusting the angular displacement of each control-bladedevice for varying the proportions by which the high-pressure air-streamis split between the two duct-entry openings of the pair ofduct-openings associated with that respective control-blade; and whereineach control-blade device comprises means defining a plurality ofparallel passages for directing air of the high-pressure air stream intothe two duct-entry openings of its associated pair of duct-entryopenings.